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Thunderbolt on Windows with Asus, Intel and Promise
Date: Jun 12, 2012
Author: Marco Chiappetta
Introduction and Thunderbolt

We have been talking about Intel's Thunderbolt technology here at HotHardware since well before it received its official name. Way back in the day, Thunderbolt went by the Intel codename "Light Peak". We had discussed Intel’s Light Peak technology on a number of occasions over the last few years and caught glimpses of the technology at work at past Intel Developers Forums.

Light Peak eventually matured into what now is known in the market as Thunderbolt technology, which debuted initially as an Apple I/O exclusive last year. As we mentioned in our IDF coverage a few years ago, Light Peak was being developed by Intel in collaboration with Apple. So it wasn't a huge surprise that Apple got an early exclusivity agreement, but there were actually a number of other partners on board as well, including Aja, Apogee, Avid, Blackmagic, LaCie, Promise and Western Digital.

As its codename implied, Light Peak initially used optical cables for data transfer. But the original optical connections discussed with Light Peak have since been complimented by less expensive copper cables as well. If you’re unfamiliar with Light Peak, now known as ThunderBolt, it is a high-speed, dual-protocol I/O technology (PCI Express and DisplayPort) designed for high performance and to simplify installations of bandwidth hungry components.

Thunderbolt has dual, bi-directional channels that offer up to 10Gbps of bandwidth per port. For comparison, USB 3.0 offers 5Gbps per port. The Thunderbolt connections are also low latency with accurate time synchronization mechanisms down to about 8ns, they offer up to 10W of power over the cable for bus-powered devices, and because ThunderBolt has native protocol support, existing drivers for current PCIe devices should be compatible, with minor, or potentially no tweaks necessary.

Thunderbolt is enabled by a physical Thunderbolt controller, which connects to a system's PCH (Platform Controller Hub) through four PCI Express lanes. Intel Thunderbolt controllers feature integrated Thunderbolt and PCI Express switches and can support either one or two connectors. The connectors themselves are of the mini-DP variety (as you'll see on the next page).

We should point out, that up to seven devices can be daisy-chained off a single Thunderbolt connector, although there are limitations as to what can be connected. No more than two DisplayPort enabled monitors can be connected at a time, and those monitors must support the DP1.1a standard. At this time, there is also an issue with hot plugging of storage devices in Windows environments. At the moment, Thunderbolt storage devices must be connected to a PC running Windows before the system is powered up or the system may need to be restarted if the device is connected to an active Windows system. We're told that future driver updates should alleviate this issue and that those drivers should be available relatively soon.

Alternatively, there are other ways to work around the current hot plugging limitation. Intel and Asus have informed us that their boards, which we'll show you on the next page, have special BIOS code that will allow for hot plugging.  Here's exactly how Intel explains their fix, "We have special code in our BIOS which allows hot plugging of storage devices even in cases where hot plug is not supported by such devices. Storage devices that are currently available today ship by default to not support PCIe hot plug due to driver limitations provided in Windows 7. Typically, the expected behavior of these TBT devices is that they must either be connected to your system in a powered off state or when attached to your systems in active windows a system restart is required in order to correctly allocate resources for the device. The DZ77RE-75K Intel Desktop Board has implemented a BIOS hot plug feature so that, much like USB, when one of these devices is attached to your computer in an active windows environment no system restart is needed. Rather, BIOS enumerates the drive and works with windows to allocate the appropriate resources needed for the device to function without a system restart."

Asus does something similar to Intel, as shown in the slide above.

Intel and Asus Thunderbolt Motherboards

To test Thunderbolt under Windows, we got our hands on a couple of high-end motherboards that have the technology built-in. First up we have the Intel DZ77RE-75K. The DZ77RE-75K is a member of Intel’s Extreme Series of motherboards, and as such, features the black and dark blue color scheme of its predecessors and a full complement of overclocking capabilities.



Mini-DP / Thunderbolt Connector on the Intel DZ77RE-75K motherboard

As you’d expect from an Intel-built motherboard, DZ77RE-75K exploits all of the features inherent to its Z77 Express chipset and adds a few more, like Thunderbolt obviously, and Firewire, through the use of a third-party controller. The board also features Intel’s “Fast Boot” technology, which speeds the boot process by eliminating the need to complete a full POST when the hardware and configuration of the system is unchanged from the previous boot.

Like other Intel Extreme Series boards, the DZ77RE-75K also supports Extreme Memory Profiles (XMP 1.3) for easy high-speed memory configuration and includes an extensive set of overclocking tools via an excellent UEFI Intel is calling their Visual BIOS. We should point out that those overclocking tools are not only available via the UEFI, but also through a Windows-based application called the Intel Extreme Tuning Utility, or Intel XTU. XTU gives users the ability to tweak numerous performance-related options and monitors system temperatures and fan speeds. “One Touch” overclocking options are also available via a simple slider for those that want a quick and easy speed boost, without doing much tweaking.


The DZ77RE-75K features heavy-duty heatsinks for the chipset and voltage regulation modules, integrated power and reset switches, solid capacitors, and a POST code error reporter, along with a number of LED status indicators. The board is outfitted with three PCI Express x16 slots as well, with full support for both NVIDIA’s SLI and AMD’s CrossFire multi-GPU technologies.

Although the sample we received was a pre-production model , and as such its bundle may change, the DZ77RE-75K we tested included an Intel “Extreme Series” mouse mat, a quick installation guide, a custom I/O shield, an SLI bridge, a driver / utility CD, and a bay mountable cage with dual USB 3.0 ports.

Next up, we have the Asus P8Z77-V Premium. The P8Z77-V Premium is one of the most feature rich motherboards we have ever come across, in terms of both its hardware and software.


Mini-DP / Thunderbolt Connector on the Asus P8Z77-V Motherboard

In addition to exploiting all of the features inherent to the Z77 Express chipset, the P8Z77-V Premium offers additional USB 3.0 support by way of discrete ASMedia controllers, Bluetooth and Wi-Fi connectivity, additional SATA 6Gbps ports, Asus “Dual Intelligent Processors 3”, and of course, Thunderbolt connectivity. The Dual Intelligent Processors consist of Asus’ EPU unit, which we’ve covered in the past, and the TurboV processing unit. The processors work together with the P8Z77-V Premium’s programmable digital VRM (DIGI+ VRM) and give users the ability to monitor and adjust power delivery on the fly. According to Asus, the combination of the programmable digital VRM and Dual Intelligent Processors 3 results in superior power efficiency and longevity.

Along with the aforementioned items, the P8Z77-V Premium is also outfitted with a PLX PCI Express switch, which gives the board to the ability to have all of its full length expansion slots enabled with full bandwidth at all times, regardless of the CPU installed.

Another great feature of the Asus P8Z77-V Premium is an integrated mSATA connector which comes populated with a 32GB SSD. And we should point out that the P8Z77-V Premium comes with a newer SSD cache controller that offers higher performance than the controller used on some of Asus' initial Z77 board. The 4 port controller on the  P8Z77-V Premium has a x2 link instead of x1, and users can run dual SSDs in SSD Caching mode with dual mechanical HDs or users can take a larger single volume and extend performance further by using up to three SSDs for caching.


The P8Z77-V Premium has a couple of other interesting features as well. For example, you can flash this board’s BIOS even if there is no CPU or memory installed via its “USB BIOS Flashback” feature. It also supports the USB Attached SCSI Protocol, which can be enabled via Asus’ AI Suite software, to boost USB 3.0 throughout by as much as 170% (we have an article in the works specifically exploring this feature).

The Asus P8Z77-V Premium also supports SLI and CrossFireX, DTS Surround, and Asus includes a copy of their AI Suite II, which gives users easy access to all of the Asus proprietary features mentioned here in a single software package. In addition, the P8Z77-V Premium also sports an excellent UEFI with one-click overclocking and tuning that’s easily navigable using a mouse.

Bundled with the Asus P8Z77-V Premium were a user’s manual, driver / utility CD, a Wi-Fi & Bluetooth module (with dual external antennas), a package of front panel header quick disconnects, an I/O shield, SLI bridge, and six SATA cables.

Promise Pegasus R4 Thunderbolt DAS Array

In addition to the Intel and Asus motherboards featured on the previous page, we also scored a Promise Pegasus R4 Thunderbolt-enabled RAID enclosure to see how Thunderbolt behaved under Windows. We should point out, however, that Promise offers two Pegasus RAID enclosures, the four-bay R4 you see pictured here and a higher-end six-bay model, aptly called the Pegasus R6.

The Promise Pegasus R4 has a clean, minimalist design aesthetic. Save for a single glossy, black strip of plastic running down the left-front of the enclosure, the entire device has the same brushed metal finish throughout. The R4’s only button, its power switch, resides at the top of the black strip which adorns the front. The rest of the front is dominated by the R4’s four drive bays, in a setup similar to most NAS devices currently on the market. The actual drives are mounted into trays, which slide into the bays and are locked in place by simple latch mechanism. The build quality of the trays and bay mount seems very good; everything fits together well and has a sturdy feel.



The sides, top, and bottom of the Pegasus R4 are mostly bare, but there are a few things to see on the back. At the very top of the back-side of the R4 is a 9-pin I/O port, adjacent to the device’s pair of Thunderbolt ports. There’s also a couple of fan grilles on the back of the R4 to allow the device’s main cooling fan to expel warm air from the system and for the smaller fan to exhaust warm air from the power supply. Underneath the smaller fan grill is a 3-prong power connector. Although Thunderbolt allows for power delivery through its cable up to 10W, that’s not enough juice to power the R4, so it needs to be connected to an electrical outlet as well.


Inside our Promise Pegasus R4 were a quartet of Hitachi 1TB drives, initially configured for operation in RAID 5 mode, but the device also supports RAID 0, 1 and 10. Configuring and connecting the device couldn't be any easier. Simply connect the Thunderbolt cable to the PC and R4, install the drivers, and you're done. An easy to use setup utility give user's the ability to log in and see device/drive status and configure the RAID mode. Once connected to the system, the array acts like any other drive attached to the system. 

Next, we'll fire up this TB-enabled RAID array and see what sort of throughput it offers.

Thunderbolt Performance in Windows

With up to a theoretical peak bandwidth of 1.25GB/s (10 Gbps) per Thunderbolt port, there’s no way four standard hard drives are going to tax the Thunderbolt connection, but we did some testing with the R4 running in RAID 5 and RAID 0 modes anyway.

RAID 5 DAS Performance with Thunderbolt
Measuring bandwidth and throughput of Thunderbolt external storage

And just for good measure, we’ve got some comparison numbers from a OCZ Vertex 3 SSD connected to our test machine using an external USB 3.0 enclosure.


Promise Pegasus R4
RAID 5 (4x1TB)

Promise Pegasus R4
RAID 0 (4x1TB)


Promise Pegasus R4
RAID 5 (4x1TB)

Promise Pegasus R4
RAID 0 (4x1TB)

We only provide the USB 3.0 SSD data here as a point of reference, to show you what kind of performance can be expected from a basic USB 3.0 enclosure with a fast SSD installed, in our case a 480MB OCZ Vertex 3. Max theoretical throughput for this SSD is around 550MB/sec for reads and 525MB/sec for writes, so its close to the theoretical bandwidth of the USB 3.0 interface (625MB/s), which is typically never achieved but in practice performs closer to 400MB/s or around 3.2Gbit/s.

As you can see, although the Promise Pegasus R4 external RAID setup doesn't come close to approaching the theoretical peak of the Thunderbolt port, the array does perform very well. In RAID 5 mode, we saw transfer speeds in CrystalDiskMark approach 380MB/s. That number increased to 512MB/s with the four drives configured in RAID 0.

The ATTO Disk benchmark, showed a best case scenario transfer speed of over 900MB/s, but we only tested a small portion of the multi-terabyte volume. The CrystalDiskMark numbers are more indicative of real world sequential and random read/write performance.
Our Summary and Conclusion

Thunderbolt has been available on some Apple systems for over a year now and it’s been met with mostly positive results. There are also a handful of Thunderbolt compatible devices already on the market thanks to Apple’s head-start, from the likes of Promise, Lacie, WD and others. On the Windows front, however, Thunderbolt is still in its infancy and there are still a few bugs to work out of systems and solutions, like the hot plugging issue we mentioned earlier.

With that said, Thunderbolt on Windows has a lot of promise. We’re not confident that mainstream users will be very interested at first for the simple fact that a basic USB 3.0 external drive will likely offer enough performance and capacity for the average usage model. Content creators or video professionals that need massive amounts of fast storage are likely to be much more enamored by Thunderbolt though. For all intents and purposes, an external RAID enclosure like the Promise Pegasus R4 we’ve featured here performs just like an array of internal drives in a system; bandwidth and latency with Thunderbolt attached storage devices is impressive indeed.

The other question is whether or not desktop systems really need Thunderbolt when drives can just be attached internally. Obviously, if you’ve got the necessary SATA ports and bays available, a multi-drive RAID array can easily be configured, but you wouldn’t have the benefit of easy portability. By that, we don’t mean portability from location to location (although that is an option), but portability from system to system. These first couple of Thunderbolt-enabled motherboards are also quite expensive. We don’t have street prices for the Intel mobo just yet, but the Asus P8Z77-V Premium is currently selling for about $399. That’s pretty pricey for a Z77 motherboard, even though it is arguably the most feature laden board you’re likely to come across at this time. We should also point out that Asus does have some more affordable options as well, including the P8Z77-V Pro, which will be available this week at $259, and the company’s upcoming $40-ish Thunderbolt EX card which will work with eleven different Asus motherboards, with prices as low as about $125 for an H77-based model.

For now, Thunderbolt is likely to remain somewhat of niche interface for content creation professionals in need of fast access to big storage volumes. Moving forward, however, as Thunderbolt gets integrated into more and more systems, software and as device support improves, its impact could be much more widespread, especially with mobile devices. Having Thunderbolt on next-gen Ultra thin laptops, tablets or convertibles opens up a world of possibilities for docking stations and similar accessories. The bandwidth and daisy-chaining capabilities enabled by Thunderbolt will make it possible to attach a mobile device to a single, thin cable and access multiple storage volumes, displays and other peripherals that will perform as if they were internal system components. Glorious bandwidth; there is no substitute.

  • Good Performance
  • Easy To Setup
  • Daisy Chain Multiple Devices From a Single Port

  • High Costs
  • USB 3.0 Fast Enough For Mainstream PC Users
  • Initial Driver Bugs

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